The present invention relates to an aluminum wheel rim and to a method for producing said rim and, more particularly, to an aluminum wheel rim and to a method for producing same wherein the aluminum wheel rim has a light weight and a good appearance as well as an appropriate mechanical strength distribution in its entirety without any difficult process and failure.
An aluminum wheel for use in a vehicle which is made of aluminum or aluminum alloy has advantages in that it has a light weight and a unique glossy appearance without requiring any particular metal plating process, while the production thereof requires less energy, so that it has recently been developed widely.
The prior art aluminum wheel has been produced in general by a casting process using sand or metallic molds or by a die casting process. Therefore, the metallic structure of such an aluminum wheel is basically of a casting structure. Thus, it is difficult to obtain sufficient mechanical strength required for such a wheel, and, therefore, the wall thickness of the wheel must necessarily be increased to achieve the required mechanical strength thereby resulting in an increased weight of the wheel at the sacrifice of the merit of an aluminum wheel characterized by the light weight thereof.
In order to avoid the above described disadvantages of the aluminum wheel, it has been proposed to divide the wheel into two or three parts such as into a rim portion and a disc portion to be assembled therewith later so that a rolling process can be applied to some parts of the wheel such as the rim portion requiring an increased mechanical strength. Thus, the rim portion has been produced by a roll working process from a rolled plate which had been bent into a cylindrical form with end edges joined together. However, when the rim portion is produced by the roll working process, it can not be avoided that thinned portions tend to appear in the thus produced rim portion at the very positions where an increased mechanical strength is required. Thus, the thickness of the material or rolled plate from which such a rim portion is to be produced by the roll working process must necessarily be increased so as to insure the required mechanical strength in such thinned portions of the rolled rim portion. It also causes an increase in weight of the rim portion at the sacrifice of the merit of the aluminum wheel described above and disadvantages in that it requires increased energy for producing the rim portion thereby forfeiting economy in the production of the aluminum wheel.
The present invention aims at avoiding the above described disadvantages of the prior art aluminum wheel and the method for producing same.